Frontal impacts were the number one killer of vehicle occupants in automobile accidents with about 16,000 fatalities each year. Side impacts were the second cause of automobile related deaths with about 8,000 fatalities each year. The number of fatalities in frontal impacts as well as side impacts has been decreasing due to the introduction of airbags and mandatory seatbelt use laws.
Several automobile manufacturers are now using side impact airbags to attempt to reduce the number of people killed or injured in side impacts. The side impact problem is considerably more difficult to solve in this way than the frontal impact problem due to the lack of space between the occupant and the side door and to the significant intrusion of the side door into the passenger compartment which typically accompanies a side impact.
Some understanding of the severity of the side impact problem can be obtained by a comparison with frontal impacts. In the Federal Motor Vehicle Safety Standard (FMVSS) 208 49 kph crash test which applies to frontal impacts, the driver, if unrestrained, will impact the steering wheel at about 30 kph. With an airbag and a typical energy absorbing steering column, there is about 40 cm to about 50 cm of combined deflection of the airbag and steering column to absorb this 30 kph difference in relative velocity between the driver and vehicle interior. Also, there is usually little intrusion into the passenger compartment to reduce this available space.
In the FMVSS 214 standard crash for side impacts, the occupant, whether restrained or not, is impacted by the intruding vehicle door also at about 30 kph. In this case there is only about 10 to 15 cm of space available for an airbag to absorb the relative velocity between the occupant and the vehicle interior. In addition, the human body is more vulnerable to side impacts than frontal impacts and there is usually significant intrusion into the passenger compartment. A more detailed discussion of side impacts can be found in a paper by Breed et al, “Sensing Side Impacts”, Society of Automotive Engineers Paper No. 940651, 1994, which is incorporated by reference herein.
Ideally, an airbag for side impact protection would displace the occupant away from the intruding vehicle door in an accident and create the required space for a sufficiently large airbag. Sensors used for side impact airbags, however, usually begin sensing the crash only at the beginning of the impact at which time there is insufficient time remaining to move the occupant before he is impacted by the intruding door. Even if the airbag were inflated instantaneously, it is still not possible to move the occupant to create the desired space without causing serious injury to the occupant. The problem is that the sensor that starts sensing the crash when the impact has begun, is already too late, i.e., once the sensor detects the crash, it is usually too late to properly inflate the airbag.
There has been discussion over the years in the vehicular safety community about the use of anticipatory sensors so that the side impact accident could be sensed before it occurs. Prior to 1994, this was not practical due to the inability to predict the severity of the accident prior to the impact. A heavy truck, for example, or a tree is a much more severe accident at low velocity than a light vehicle or motorcycle at high velocity. Further, it was not possible to differentiate between these different accidents with a high degree of certainty.
Once a sufficiently large airbag is deployed in a side impact and the driver displaced away from the door and the steering wheel, he will no longer be able to control the vehicle that could in itself cause a serious accident. It is critically important, therefore, that such an airbag not be deployed unless there is great certainty that the driver would otherwise be seriously injured or killed by the side impact. Anticipatory sensors have heretofore not been used because of their inability to predict the severity of the accident. As discussed more fully below, the present invention solves this problem and therefore makes anticipatory sensing practical. This permits side impact airbag systems that can save a significant percentage of the people who would otherwise be killed as well as significantly reducing the number and severity of injuries. This is accomplished through the use of pattern recognition technologies such as neural networks such as discussed in U.S. Pat. No. 5,829,782, incorporated by reference herein.
Neural networks, and more recently modular neural networks, are capable of pattern recognition with a speed, accuracy and efficiency heretofore not possible. It is now possible, for example, to recognize that the front of a truck or another car is about to impact the side of a vehicle when it is one to three meters or more away. This totally changes the side impact strategy since there is now time to inflate a large airbag and push the occupant out of the way of the soon to be intruding vehicle. Naturally, not all side impacts are of sufficient severity to warrant this action and therefore, there will usually be a dual inflation system as described in more detail below.
Although the main application for anticipatory sensors is in side impacts, frontal impact anticipatory sensors can also be used to identify the impacting object before the crash occurs. Prior to going to a full frontal impact anticipatory sensor system, neural networks can be used to detect many frontal impacts using data in addition to the output of the normal crash sensing accelerometer. Simple radar or acoustic imaging, for example, can be added to current accelerometer based systems to give substantially more information about the crash and the impacting object than possible from the acceleration signal alone.
The side impact anticipatory sensor of this invention can use any of a variety of technologies including optical, radar (including noise radar, Micropower inpulse radar, and ultra wideband radar), acoustical, infrared or a combination of these. The sensor system typically contains a neural network processor to make the discrimination however a simulated neural network, a fuzzy logic or other algorithm operating on a microprocessor can also be used.
With respect to prior art related to the subject matter of this application, reference is made to European Patent Publication No. 0 210 079 (Davis). Davis describes, inter alia, a radar system for use in connection with an airbag deployment apparatus to prevent injury to passengers when impact with an approaching object is imminent. Voltage level inputs representative of the distance between an object and the vehicle, the approach rate of the object with respect to the vehicle, the vehicle speed and driving monitor inputs, e.g., steering angles, turning rates and acceleration/deceleration, are all generated by appropriate detectors, weighted according to their importance to a normal vehicle operators' sensed safe or danger levels and then the weighted input voltages are summed to provide an “instantaneous voltage level”. This instantaneous voltage level is compared with a predetermined voltage level and if the instantaneous voltage level falls within a predetermined safe zone, output signals are not produced. On the other hand, if the instantaneous voltage level falls outside of the safe zone, i.e., within a danger zone, then the system can be designed to initiate deployment of the airbag on the additional condition that the vehicle speed is above a predetermined level. For example, the system can be programmed to deploy the airbag when the vehicle speed is between 35 and 204 miles per hour at a time of about 0.2 second prior to impact thereby enabling the airbag sufficient time to fully inflate.
As far as structure, Davis includes a radar system that includes an antenna assembly, a signal-processing unit and an output monitor. Davis relies on a radar signal generated by an antenna in the antenna assembly and which causes a return signal to be produced upon reflection of the radar signal against the approaching object. The return signal is received by a transceiver to be processed further in order to determine the distance between the object and the vehicle and the rate the object is approaching the vehicle. The return signal from the radar signal generated by the antenna is a single pulse, i.e., a single pixel. The elapsed time between the emission of the radar signal by the antenna and the receipt of the return signal by the transceiver determines the distance between the object and the vehicle and based on the elapsed time for a series of radar signals generated at set intervals, it is possible to determine the approach rate of the object relative to the vehicle.
In operation, the approach rate of the object relative to the vehicle, the distance between the object and the vehicle, the vehicle speed as well as other driving parameters are converted to voltage levels. Davis then uses an algorithm to weigh the voltage levels and compare the voltage levels to predetermined conditions for which airbag deployment is desired. If the conditions are satisfied by the results of the algorithm operating on the weighted voltage levels, then the airbag is deployed. In one embodiment, by appropriate manipulation of the voltage levels, false-triggering of the airbag can be prevented for impacts with objects smaller than a motorcycle, i.e., the voltage corresponding to a motorcycle at a certain distance from the vehicle is smaller than the voltage corresponding to a truck, for example at that same distance.
Davis does not attempt to recognize any pattern of reflected waves, i.e., a pattern formed from a plurality of waves received over a set period of time, from many pixels simultaneously (light and CCDs) or of the time series of ultrasonic waves. A tree, for example can have a smaller radar reflection (lower voltage in Davis) than a motorcycle but would have a different reflected pattern of waves (as detected in the present invention). Thus, in contrast to the inventions described herein, Davis does not identify the object exterior of the vehicle based on a received pattern of waves unique to that object, i.e., each different object will provide a distinct pattern of reflected or generated waves. The radar system of Davis is incapable of processing a pattern of waves, i.e., a plurality of waves received over a period of time, and based on such pattern, identify the object exterior of the vehicle. Rather, Davis can only differentiate objects based on the intensity of the. signal.
International Publication No. WO 86/05149 (Karr et al.) describes a device to protect passengers in case of a frontal or rear collision. The device includes a measurement device mounted in connection with the vehicle to measure the distance or speed of the vehicle in relation to an object moving into the range of the vehicle, e.g., another vehicle or an obstacle. In the event that prescribed values for the distance and/or relative speed are not met or exceeded, i.e., which is representative of a forthcoming crash, a control switch activates the protection and warning system in the vehicle so that by the time the crash occurs, the protection and warning system has developed its full protective effect. Karr et al. is limited to frontal crashes and rear crashes and does not appear to even remotely relate to side impacts. Thus, Karr et al. only shows the broad concept of anticipatory sensing in conjunction with frontal and rear crashes.
U.S. Pat. No. 4,966,388 (Warner et al.) relates to an inflatable system for side impact crash protection. The system includes a folded, inflatable airbag mounted within a door of the vehicle, an impact sensor also mounted within the door and an inflator coupled to the impact sensor and in flow communication with the airbag so that upon activation of the inflator by the impact sensor during a crash, the airbag is inflated.
U.S. Pat. No. 3,741,584 (Arai) shows a pressurized air container and two air lines leading to a protective air bag. An air line passes through a first valve which is controlled by an anticipatory sensor and the other air line passes through a second valve controlled by an impact detector. The purpose of having two sensors associated with different valves is to ensure that the protective bag will inflate even if one of the crash sensors does not operate properly.
U.S. Pat. No. 3,861,710 (Okubo) shows an airbag inflation system with a single airbag which is partially inflated based on a signal from an obstacle detecting sensor and then fully inflated based on a signal from an impact detecting sensor. The obstacle detecting sensor controls release of gas from a first gas supply source into the gas bag whereas the impact detecting sensor controls release of gas from a second gas supply source into the gas bag. The first gas supply source includes a first gas container filled with a proper volume of gas for inflating the gas bag to a semi-expanded condition, a first valve mechanism, a pipe between the first gas container and the first valve mechanism and a pipe between the first valve mechanism and the gas bag. The second gas supply source includes a second gas container filled with gas in a volume supplementing the volume of gas in the first gas container so that the contents of both gas containers will fully inflate the gas bag, a second valve mechanism, a pipe between the second gas container and the second valve mechanism and a pipe between the first valve mechanism and the gas bag.
U.S. Pat. No. 3,874,695 (Abe et al.) shows an inflating arrangement including two inertia-responsive switches and coupled gas-generators. The gas-generators are triggered by the switches to inflate an airbag. The switches are both crash sensors and measured acceleration produced during the collision, and thus are not anticipatory sensors. The purpose of the two switches operative to trigger respective gas-generators is to enable the airbag to be inflated to different degrees. For example, if the crash involving the vehicle is a low speed crash, then only switch is actuated and gas-generated is triggered and the airbag will be inflated to part of its full capacity.
In U.S. Pat. No. 5,667,246 (Scholz et al.), there are two accelerometers, each of which provides a signal when the value of the increase in deceleration exceeds a respective threshold value. The signal from the accelerometer is set to a first ignition stage and through a delay member to a second ignition stage. The second ignition stage also receives as input, a signal from the accelerometer and provides an inflation signal only when it receives a signal from both accelerometers. In operation, when the accelerometer sends a signal it serves to partially inflate the airbag while full inflation of the airbag is obtained only by input from both accelerometers Taniguchi (JP 4-293641) describes an apparatus for detecting a body moving around another body, such as to detect a car thief moving around a car. The apparatus includes a detection section supported on a support toll to the roof of the car. Taniguchi states that the detection section may be based on an infrared, microwave or ultrasonic sensor.